Ethnic differences in the prognostic value of coronary artery calcification for all-cause mortality

Abstract

Objectives: The purpose of this study was to evaluate the prognostic value of coronary artery calcium (CAC), a known marker of subclinical atherosclerosis, in a large, ethnically diverse cohort of 14,812 patients for the prediction of all-cause mortality.

Background: Disparities in case fatality rates for heart disease among ethnic groups are well known. In 2001, rates of death from heart disease were 30% higher among African Americans (AA) than non-Hispanic whites (NHW). Some of this variability may be due to differing pathophysiological mechanisms and effects of underlying atherosclerosis.

Methods: Ten-year death rates from all causes (total deaths = 505) were compared using risk-adjusted Cox proportional hazards models in AA (n = 637), Hispanic (HS, n = 1,334), Asian (AS, n = 1,065), and NHW (n = 11,776) populations.

Results: Ethnic minority patients were generally younger (0.3 to 4 years), more often persons with diabetes (p < 0.0001), hypertensive (p < 0.0001), and female (p < 0.0001). The prevalence of CAC scores > or =100 was highest in NHW (31%) and lowest for HS (18%) (p < 0.0001). Overall survival was 96%, 93%, and 92% for AS, NHW, and HS, respectively, as compared with 83% for AA (p < 0.0001). When comparing prognosis by CAC scores in ethnic minorities as compared with NHW, relative risk ratios were highest for AA with CAC scores > or =400 exceeding 16.1 (p < 0.0001). Hispanics with CAC scores > or =400 had relative risk ratios from 7.9 to 9.0, whereas AS with CAC scores > or =1,000 had relative risk ratios 6.6-fold higher than NHW (p < 0.0001).

Conclusions: Consistent with population evidence, AA with increasing burden of subclinical coronary artery disease were the highest-risk ethnic minority population. These data support a growing body of evidence noting substantial differences in cardiovascular risk by ethnicity.